1. Field of the Invention:
This invention relates to a closed circuit television apparatus as a supervisory system, and more particularly to a closed circuit television apparatus in which operation of a television camera is remotely controlled.
2. Description of the Prior Art:
Generally, in a closed circuit television system such as a supervisory system, a remote-controllable television camera is located at each of a plurality of different places to be observed. At a central supervisory station, a monitor for receiving video signals from the selected television camera, a controlling device for controlling the operation and coordinates of the television camera, such as up-down (tilting), left-right (panning), far-near (focusing) and wide-tele (zooming), and a switching circuit for selecting one of the television cameras to be connected to the controlling device and the monitor, are located.
The positioning of each television camera coordinates such as tilting, panning, focusing and zooming are controlled by control signals supplied from the controlling device, and the television camera transmits video signals to the central supervisory station. The switching circuit includes a switch for the video signals and another switch for the control signals, and these two switches should be interlocked with each other.
A problem with such conventional closed circuit television apparatus is that if the two switches are not interlocked due to the break-down of the switching circuit, a wrong television camera coordinates could be repositioned.
Another conventional system uses two switches to be operated independently. In such conventional closed circuit system, the attendant must operate the switch to connect the monitor to the television camera that its coordinates must be repositioned and must connect the controlling device to the same television camera separately, which is laborious, time-consuming and may cause operational error as the attendant may connect a wrong camera to the controlling device.